Why boxing kangaroos?

I read on the internet a lot about kangaroos, but only as boxing. Does anyone know why they do that?

The best answer

Rank and turf wars - wolves, wild dogs, lions, etc. use their teeth and claws, wild cattle (bison, wildebeest etc.) their horns, deer their antlers and kangaroos up their paws - which they rather use my knowledge the "legs" than the "arms", the term "pit" so watch m. E. actually not so very